The present invention relates to kitchen exhaust fans, and particularly to an apparatus capable of separating liquid components, such as oleaginous substance, from heated vapor and smoke released during a cooking process, so as to discharge the liquid components and gases through separate outlets.
Prior art exhaust fans generally include a motor-driven fan mounted in a casing having an inlet port and an outlet port for exhausting gaseous emissions generated during a cooking process in the kitchen. A problem incident to such exhaust fans is that in cooking food products of a greasy nature, especially Chinese cuisine, oleaginous components entrained in the vapor or smoke tend to be separated from same by the centrifugal force produced by the rotating fan to deposit on the fan, the interior surfaces of the casing, and the surrounding area of the inlet port. These oleaginous components accumulate in droplets, which may sometimes be spattered out from the rim of the inlet port and drop down on the food being cooked to thereby contaminate the food. Particularly, the oleaginous may also condense in large quantities to become gelatinous masses plugging the gap between the inlet port and the fan blades. Thus, periodical cleaning of the exhaust fan is required, yet it is difficult and time-consuming to remove the gelatinous masses.
Various means for overcoming the abovementioned disadvantages have been provided. For example, the inlet port of the casing may be covered with a filter screen so that larger oleaginous components are absorbed by the filter screen when gaseous emissions containing same are being drawn into the casing. There may also be provided an annular groove around the inlet port, or a hole in the lowest rear portion of the casing, so that oleaginous components centrifugally separated from the gaseous emissions in the casing may be collected in the annular groove or converged to the hole to be removed manually. However, it has been discovered through long periods of observations and experiments by the inventor that the abovementioned devices, while functional, may not achieve the desired effect. For instance, while the filter screen may entrap oleaginous components, it may also become an obstacle to the drawing in of gaseous emissions through the inlet port, thus lowering the efficiency of the exhaust fan. Consequently, when it is desired to acquire as high an efficiency as would be possible if such a filter screen were not provided, a motor of higher power would be required and hence more electrical energy would be consumed. Nevertheless, sincle the oleaginous components adhering to the filter screen may eventually reduce the porous space of the filter screen, the filter screen must be removed from the inlet port to be cleaned; otherwise, once the oleaginous components have condensed in gelatinous masses on the filter screen, they may be melted by the heat generated during a cooking process and drop down on the food being cooked under the influence of gravity, thereby contaminating the food.
The invention is directed toward an apparatus which can overcome the abovementioned disadvantages.